1. Field of the Invention
The present invention relates to an electrically heated rear screen made of laminated glass equipped with parallel connected resistive heating wires embedded in and extending horizontally in a thermoplastic interlayer, and in which the resistive heating wires at the two lateral edges of the laminated window are connected to electrical connection elements.
2. Discussion of the Background
Known electrically heated rear screens of this kind include current collecting conductors which, as a general rule, are made of strips of tinned copper foil arranged along the two lateral edges. The length of each of these resistive heating wires is equal to the width of the rear screen and each resistive heating wire is connected at each end to one of the two collecting conductors. Given that the length of the resistive heating wires is limited by the width of the window, it is necessary to use resistive wires which have a relatively high specific resistance, that is to say thin tungsten wires. These are arranged and fixed in the form of a straight or wavy line to a thermoplastic film to which the collecting conductors have already been fixed.
As a general rule, rear screens are mounted in a vehicle using an adhesive bonding technique. In order to protect the adhesive from UV radiation and to prevent the adhesive being visible from the outside, all motor vehicle windows intended to be mounted using the bonding technique are, on their surface which faces the cabin interior, equipped with an opaque decorative border, in dark-colored, preferably black, enamel. The metal collecting conductors which are arranged about 1 to 2 cm from the edge of the window are not particularly appealing from a visual point of view because of their contrast with the decorative border behind them when the window is looked at from the outside. They are therefore covered on the outside by a second opaque layer. This other opaque layer may also be a layer of a color similar to the decorative border, which is connected directly to the surface visible from the outside of the collecting conductor. Embodiments of this kind are known from document DE 19 541 609 A1.
Applying another opaque layer to the surface of the window that is adjacent to the thermoplastic interlayer with a view to covering the collecting conductors is an operation that is costly in terms of labor and which furthermore cannot be completed until the two window panes have been curved. Applying this layer as an ink to be baked prior to curving was hitherto impossible because the two panes stick together during the curving operation because the bake-on ink melts. The results obtained by coating the collecting conductors themselves with such a layer have hitherto not been appealing.